Frame Relay IP RTP Priority
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Frame Relay IP RTP Priority

Table Of Contents

Frame Relay IP RTP Priority

Feature Overview

Benefits

Related Features and Technologies

Related Documents

Supported Platforms

Supported Standards and MIBs and RFCs

Prerequisites

Configuration Tasks

Configuring Frame Relay IP RTP Priority

Verifying Frame Relay IP RTP Priority

Monitoring and Maintaining Frame Relay IP RTP Priority

Configuration Examples

Frame Relay IP RTP Priority Configuration Example


Frame Relay IP RTP Priority


This feature module describes the Frame Relay IP RTP Priority feature. It includes the following sections:

Feature Overview

Supported Platforms

Supported Standards and MIBs and RFCs

Prerequisites

Configuration Tasks

Monitoring and Maintaining Frame Relay IP RTP Priority

Configuration Examples

Feature Overview

The Frame Relay IP RTP Priority feature provides a strict priority queueing scheme on a Frame Relay permanent virtual circuit (PVC) for delay-sensitive data such as voice. Voice traffic can be identified by its Real-Time Transport Protocol (RTP) port numbers and classified into a priority queue configured by the frame-relay ip rtp priority command. The result of using this feature is that voice is serviced as strict priority in preference to other nonvoice traffic.

This feature extends the functionality offered by the ip rtp priority command by supporting Frame Relay PVCs. This feature allows you to specify a range of User Datagram Protocol (UDP) ports whose voice traffic is guaranteed strict priority service over any other queues or classes using the same output interface. Strict priority means that if packets exist in the priority queue, they are dequeued and sent first—that is, before packets in other queues are dequeued.

Benefits

The strict priority queueing scheme allows delay-sensitive data such as voice to be dequeued and sent first—that is, before packets in other queues are dequeued. Delay-sensitive data is given preferential treatment over other traffic. This process is performed on a per-PVC basis, rather than at the interface level.

Related Features and Technologies

The Frame Relay IP RTP Priority feature is related to the following features:

IP RTP Priority

Class-based weighted fair queueing (CBWFQ)

Priority queueing

Weighted fair queueing (WFQ)

Related Documents

Quality of Service Solutions Configuration Guide, Cisco IOS Release 12.0

Quality of Service Solutions Command Reference, Cisco IOS Release 12.0

Class-Based Weighted Fair Queueing

IP RTP Priority

Supported Platforms

Cisco 1003

Cisco 1004

Cisco 1005

Cisco 1600 series

Cisco 2500 series

Cisco 2600 series

Cisco 3600 series

Cisco 3800 series

Cisco 4000 series (Cisco 4000, 4000-M, 4500, 4500-M, 4700, 4700-M)

Cisco 5200 series

Cisco 7000 series

Cisco 7200 series

Cisco 7500 series

This feature runs on the platforms listed. However, it is most useful on voice supported platforms, such as the Cisco 2600 series, Cisco 3600 series, Cisco 7200 series, and Cisco 7500 Route Switch Processor (RSP) series.

Supported Standards and MIBs and RFCs

Standards

None

MIBs

No new or modified MIBs are supported by this feature.

RFCs

None

Prerequisites

Frame Relay traffic shaping (FRTS) and Frame Relay Fragmentation (FRF.12) must be configured before the Frame Relay IP RTP Priority feature is used.

Configuration Tasks

Configuring Frame Relay IP RTP Priority (Required)

Verifying Frame Relay IP RTP Priority (Optional)

Configuring Frame Relay IP RTP Priority

To reserve a strict priority queue on a Frame Relay PVC for a set of RTP packet flows belonging to a range of UDP destination ports, use the following command in map-class configuration mode.


Note Because the frame-relay ip rtp priority command gives absolute priority over other traffic, it should be used with care. In the event of congestion, if the traffic exceeds the configured bandwidth, then all the excess traffic is dropped.


Command
Purpose

Router(config-map-class)# frame-relay ip rtp priority starting-rtp-port-number port-number-range bandwidth

Reserves a strict priority queue for a set of RTP packet flows belonging to a range of UDP destination ports.


Verifying Frame Relay IP RTP Priority

To verify the Frame Relay IP RTP Priority feature, use one of the following commands in EXEC mode:

Command
Purpose

Router# show frame relay pvc

Displays statistics about PVCs for Frame Relay interfaces.

Router# show queue interface-type interface-number

Displays fair queueing configuration and statistics for a particular interface.

Router# show traffic-shape queue

Displays information about the elements queued at a particular time at the VC data link connection identifier (DLCI) level.


Monitoring and Maintaining Frame Relay IP RTP Priority

To tune your RTP bandwidth or decrease RTP traffic if the priority queue is experiencing drops, use the following command in EXEC mode:

Command
Purpose

Router# debug priority

Displays priority queueing output if packets are dropped from the priority queue.


Configuration Examples

Frame Relay IP RTP Priority Configuration Example

Frame Relay IP RTP Priority Configuration Example

The following example first configures the Frame Relay map class called voip and then applies the map class to PVC 100 to provide strict priority service to matching RTP packets:

map-class frame-relay voip
 frame-relay cir 256000
 frame-relay bc 2560
 frame-relay be 600
 frame-relay mincir 256000
 no frame-relay adaptive-shaping
 frame-relay fair-queue
 frame-relay fragment 250
 frame-relay ip rtp priority 16384 16380 210
 
   
interface Serial5/0
 ip address 10.10.10.10 255.0.0.0
 no ip directed-broadcast
 encapsulation frame-relay
 no ip mroute-cache
 load-interval 30
 clockrate 1007616
 frame-relay traffic-shaping
 frame-relay interface-dlci 100
  class voip
 frame-relay ip rtp header-compression
 frame-relay intf-type dce
 
   

In this example, RTP packets on PVC 100 with UDP ports in the range 16384 to 32764 will be matched and given strict priority service.